Ball grid arrays are available commercially from AMKOR/ANAM, Korea. Such arrays comprise a plastic film with an array of recesses, each recess providing a receptacle for a solder ball. The arrays are available in strips which may be detached from one another. The recesses are small and closely spaced from one another. Thus the placement of solder balls reliably into the recesses is a difficult task.
Various techniques have been devised to place the solder balls in the recesses. One technique, developed by employs a vacuum chuck with a number of holes corresponding to the recesses in the ball grid array. The holes are defined in a shift plate which moves to release the balls into the ball grid array therebeneath when the vacuum is removed. Another method employs a "dip strip" which captures the balls and then mates with the ball grid array to transfer the
Such techniques have been found to be unreliable and expensive to implement. Also, particularly in the latter technique, the balls are not accurately positioned in the recesses. Also, such techniques do not reliably populate the ball grid array Further, the recesses of the array are larger than the solder balls and the above-noted mating technique places the balls in various positions in the recesses, in positions which are sufficiently different to be misplaced when integrated with a microcircuit, thus rendering the microcircuit inoperative.